At least 3,000 people are sleeping rough on the streets of Paris, according to data from the city's first ever homelessness census which authorities warned Wednesday were likely a serious underestimate.

For the first time, the municipality decided to count the number of its homeless.

"Nearly 3,000 people were counted [...] in the Parisian public space," the first deputy mayor of Paris Bruno Julliard told a news conference, adding that this figure was "probably far below reality".

Some 1,700 Parisian volunteers and 300 officials carried out the census overnight on February 15th, going street by street counting the number of people huddled in sleeping bags in doorways or camped out in tents.

It is hoped that the project, known as Nuit de la Solidarite (Night of Solidarity), will help the city better distribute its services.

Homeless people were also surveyed about their housing and health problems, collecting data that Socialist Mayor Anne Hidalgo hopes will allow authorities to design better policies to help those on the streets.

Deputy mayor Bruno Julliard, unveiling the results, warned that the figure of 2,952 people sleeping rough -- added to 672 in emergency winter shelters -- was a low estimate.

"Car parks were not taken into account and nor were the staircases of buildings, notably social housing," he said, pointing to places where people typically take shelter in the winter.

President Emmanuel Macron had last July promised to end rough sleeping across France entirely by the end of 2017, and acknowledged last month that he had failed to meet that ambitious goal.

"We've failed there," Macron admitted last week, pointing to a continuing influx of African and South Asian migrants and refugees who often end up camping out.

Visitors to Paris are often shocked by the poverty that exists in some parts of the capital, especially the omnipresent beggars on the metro and the migrants' tents perched along the Canal Saint-Martin.